Dogs and cats have lived together forcibly by us humans as well behaved pets for decades. But is this togetherness just a simply show put on to please us and live comfortable within the protection and care of us humans? Are dogs and cats natural sworn enemies and as soon as we turn our backs they silently go at each other's throat? But the sad thing is, it has happened many times before where pet owners dog have killed the cat or even the cat that strayed inside their home which belonged to the neighbors. It is a very sad part of pet ownership, not the fact that the cat has died only, but that now you know your dog is capable of killing and a mis-trust factor may develop between your dog and you especially if little children are around. But with that said, let us look at some reasons why your dog may attack and wound or kill the cat.

1. Dog Has Gotten Senile
This can surely happen. Some dogs will develop mental issues which may cause the dog to have erratic behaviors such as:

Generalized Anxiety

Staring at Walls

Low Threshold for Aggression

Receptivity behaviors

Elimination Disorders

Decreased activity levels.

This low threshold for aggression may see the animal acting out on other animals such as other dogs and your cat.

2. Suffers from Inter Dog AggressionThis occurs when the animal becomes overly aggressive towards animals within the same household. This over aggression is easily spread towards other animals especially cats. This over aggression will lead to the dog attacking the cat and can cause serious wounds or even death.

3. It has an Overwhelmed Predatory Drive
Just like any other non domesticated animals such as the large cats, African wild dogs, wolves etc. There is always a genetically predatory drive within these animals and your domesticated dog is no different. Animals can be tamed, but they will always possess that natural hunting instinct. This natural instinct may sadly be triggered in your dog which may cause your dog to kill the cat.

4. Cat May Be Too Close For Comfort
Some dogs will tolerate a cat living nearby, but will definitely get frustrated if the cat moves into his/her territory and becomes too close for comfort. We must remember that all animals are territorial. Some don't want to share territory with other animals of their kind much less other species of animals. The dog may kill the cat if it gets into the dog's space a bit too often.

5. Learnt Aggression
Some dogs are trained to be aggressive towards other dogs and any other animal they may encounter. You may have a beautiful dog living with you for years. Then you decide on getting a cat. Everything will seem nice once you are around, but the moment you leave them alone for awhile, the dog's learnt behavior chips in. He will attack the cat and wound or kill it. Sometimes this aggression is seen right away with the introduction of this new animal. The dog will bark aggressively and growl. If you feel you have a dog with learnt aggression towards other animals, seek advice from a good dog trainer.

Why My Dog Killed My Cat?

What To Do After The Dog Attacks The Cat.
Remember, this is going to be painful moving forward, as the cat the dog killed is either your beloved pet or someone else beloved pet. It could be a cat which belonged to your neighbors as well. ​ There will be anger on some part, blame and of course grief. If your dog is responsible for killing someone else's cat, even if the animal strayed on to your property, show some condolence and remorse to the other pet owner. Even agree to help out with cost of final arrangements. Then you will have to make critical decisions to assess your dog to find the root cause and ensure that that horror does not reoccur.

Seek Professional Help

First get the animal to a Vet to ensure that the animal is within it's sound mind. If the vet passes the animal as being fit and healthy in mind and body, then seek an Animal behavior Training Specialist. This Specialist will help to introduce a calmer demeanor in your dog towards other dogs and animals. So basically you are introducing your dog to behavior modification.

Manage Your Dogs Environment

Ensure that your dog is secure and not able to trespass in anyone's home or on the street. If your neighbors have cats, speak to them so they can ensure that the cat is not able to roam in other peoples property especially where there is likely to be a dog.

Protect Your Other Cats and even Small Dogs

Don't just assume that this is a one off behavior and it should be forgotten and swept under the rug. If your dog attacks and kills a cat, chances are that it may attack another cat and do the same. Keep your dog away from any other pet which resides with you. Remember, you must prevent recurrence at all times.

Dog Killed The Cat, What About The Kids?
I am sure a few dog owners will have the thought of putting down the animal in fear that it may end up attacking the child one day. My advice to you is to always ensure that your child/children remain safe. Keep the dog away from the kids until you are able to make a final decision on what course of action to take. But this does not mean you should throw the animal behind a bar everyday and feed it with sticks like a man made beast. If you decide on keeping the dog, ensure that when the kids are out with the dog, there is substantial supervision at all times.

Conclusion
If your dog was not trained to be tolerant of other animals from pup stage, chances are that your dog may end up growing and chasing or being aggressive to other small animals. Many people will get Dogs from shelters and other facilities that are fully grown and may be suffering from emotional ailments you simply cannot see until it becomes too late. Always reintroduce positive behavior in your dog. Get the dog retrained, introduce new animals and hope the dog grows tolerable and peaceful towards other creatures. Remember, professional help should always be sought when you are faced with situations like this.